//: concurrency/CallableDemo.java
package concurrency;

import java.util.concurrent.*;
import java.util.*;

class TaskWithResult implements Callable<String>
{
    private int id;
    
    public TaskWithResult(int id)
    {
        this.id = id;
    }
    
    public String call()
    {
        return "result of TaskWithResult " + id;
    }
}

public class CallableDemo
{
    public static void main(String[] args)
    {
        ExecutorService exec = Executors.newCachedThreadPool();
        ArrayList<Future<String>> results = new ArrayList<Future<String>>();
        for (int i = 0; i < 10; i++)
            results.add(exec.submit(new TaskWithResult(i)));
        for (Future<String> fs : results)
            try
            {
                // get() blocks until completion:
                System.out.println(fs.get());
            }
            catch (InterruptedException e)
            {
                System.out.println(e);
                return;
            }
            catch (ExecutionException e)
            {
                System.out.println(e);
            }
            finally
            {
                exec.shutdown();
            }
    }
} /*
   * Output: result of TaskWithResult 0 result of TaskWithResult 1 result of TaskWithResult 2 result of TaskWithResult 3
   * result of TaskWithResult 4 result of TaskWithResult 5 result of TaskWithResult 6 result of TaskWithResult 7 result
   * of TaskWithResult 8 result of TaskWithResult 9
   */// :~
